Apparatus and method for producing sound



Sept. 8, 1931. H. HLJEIBER ET AL 1,822,579

APPARATUS AND METHOD FOR PRODUCING SOUND Original Filed Oct. 3, 1930 l ll l l l l I l l l l llll||llIIll|llIl|llflllllllllllllmlllllllmlllllllllllllllllllllllll||llllllllllllllllllllllllllllllllllll I l lIIlll|lIIllllllllllHlHlllHlll IM/wanton HerurgHueber Erwin C. Hol-Low be effected by observance Patented Sept. 8, 1931UNITED STATES PATENT-OFFICE t HENRY HUEBER, OF BUFFALO, AND

. o ERWIN C. HORTON, OF HAMBURG, NEW YORK, AS-

, SIGNORS TO TRICO PRODUCTS CORPORATION, OF BUFFALO, NEW VYORK APPARATUSAND METHOD FOR PRODUCING- SOUND @riginal application iled October 3,1930, Serial No.- 486,228. Divided and this application filed March 21,

1931. Serial This invention relates to methods of and devices forproducing sound of a desired or predetermined pitch, tonal quality andintensity.

The inventive method is particularly desirable inconnection with theprovision of warning signals for use on automobiles, boats or othervehicles.

Heretofore various methods and devices have been proposed for thispurpose in which devices and methods as a rule provision has been madefor the production of sound waves from a vibrant media or body which isnot uniform or consistent and-in which it is not possible to uniformlyvibrate or movethe sound wave generating means in frequency commensurateto or harmonious with the natural periodicity of the media beingoperated. upon, whereby a considerable portion of the sound waves areunintentionally dampened, distorted or modiiied, preventing. theacquiring of true sound wave yintensity and dispersion.

ln devices heretofore provided the tendency has been to providerelativelygreat intensity of sound without attention being paid to thetrue form of the sound wave produced, with the result that ragged ordistorted waves or tones characterized any dev-ice having greatintensity or carrying eect as being obnoxious or raucous to the humanear.

We have ascertained that a true and most cective sound wave intensitymay be secured by the generation of the waves in media which issubstantially uniform and natural and in which the media is acted uponby mechanical means in such fashion that a regenerative` resonant effectis i obtained, such mechanical means for initiating the sound wavesbeing adjusted to frequency commensurate and in synchronism an rhythmwith the media. The generation of sound waves of true form and maximumintensity will of? such principles and produce a warning note or signalwhich will have greater and more effective intenn sity or carryingpowers and at the same time vby reason' of the true and clear tone and dthe construction the the vibratory periodicity of` form of the noteproduced, will not be ob.

noxious to the ear.

In the accompanying drawings, we have illustrated a device embodying astructure illustrative of that which will serve to carry into effect theprinciples of this invention.

Fig. 1 is a side elevation of a horn embodying one form of ourinvention;

Fig. 2 is an enlarged longitudinal section through the sound generatingend of the horn;

Fig. 3 is a transverse section through the sound generator housing orcasing;

Figs. 4 and 5 are diagrammatic illustrations made for the purpose ofmore clearly setting forth the operation of our horn.

In the device illustrated, a hollow chamber 1 is provided comprising inthis particular embodiment, a front sectionQ and a back section 3suitably secured together as by fasteners 3a. 'Ehe front section may, asshown, be provided-with a tubular boss 4 on which is mounted a resonator5. Within the casingl an annular valve seat 6. 8 desis provided ignatesa vibratory valve which constitutes apart of the sound wave' generator.As illustrated, a substantial portion of the body `of the trumpetadjacent the valve seat is of` restricted diameter or bore so as toprovide a substantial amount of friction to a column of air in saidtrumpet and to in effect increase the inertia of any column Sof airtherein.

The valve 8 is resiliently supported with respect to its seat 6, as, forexample, by means of the radial springsll which are shown as four innumber der tension from the inner wall of the sound box to the valve 8.A function of these springs is to normally urge the valve onto or towardits seat. To facilitate and simplify box section 2 is provided withanchoring portions 18 with which the outer ends of the springs areengaged, and the/valve 8 is formed with an axial extension or hub 14which carries the flange 12 to which the inner ends of the springs areconnected. The springs therefore serve to resiliently hold the valve onits seat 6`so as to seal or close communication between the trumpet andextended un-l passage and the valve chamber within the sound box, thisengagement of the'valve with its seat beiner made light or firm by'thead- -justability of one or more of the parts. Communication isestablished between the sound box and the intake manifold, or othersource' of suction, through a conduit 16, which com munication iscontrolled by a readily accessible valve, not shown.

The valve 8 may be formed independently of its hub or stem 14 and-therefore may embody differing characteristics and materials in itsmake-up. The spring lsupport for the valve permits bodily movement ofthe latter unguided otherwise in its movement than by the radialsprings. Thus the valve is given a spring suspension permitting thevalve to have bodily movement with `or without a tension rocking ortilting motion. Therefore, the inertia of the rapidly moving vifbrator8, 14, is given tens1oned as well as guided motion through the springsuspension.

. air stream past the valve 8 and through the valve chamber 1. Thisunseating of the valve tends to equalize the pressures on both sides ofthe valve so that the s rings will return the valve to its seat,followlng which the pres- -sure within the chamber l' will again becomerarefied and the valve unseat', and then reseat, whereby a series ofcondensations and rarefactions are produced in the air, with a resultantthrowing of the air stream into vibration.

In order to render the radial spring support for thevalve more quicklyresponsive and improve upon the tone of the signal note, as well asincrease its pitch, the springs 11 are given an intermediate support, asat 17, the support being conveniently carried by the box section 3. Inorder to insure the proper tuned relationship between the rate ofvibration of the sound wave generator and the air column within thetrumpet 5, the support 17 1s made adjustable by a stud 18 which isthreaded through aboss 19 and the adjustf ment secured by a jam nut 20.

In the production of sound with this de- .vice, the chamber 1 is placedin communicationwith the source of reduced pressure, as

for example, by being connected through the conduit 16 to the intakemanifold of an internal combustion engine. By reason ofsuc-h connection,upon operation of the engine a sub-atmospheric condition ofpressure willbe created in the chamber 1 and the front end or bell of the trumpetbeing open to the atmosphere, the column of atmospheric air in.

the trumpet will push the valve 8 from its seat against the action ofthe springs 11. Starting its movement, as the valve does, withatmospheric pressure on one face and a minimum sub-atmospheric pressurecondition on the other face, as the mass of the valve and its supportingsprings is set in motion, the movement coupled with the inertia of theseparts is translated to momentum which carries the valve farther backpast its normal point of equilibrium.

The unseating of the valve permits atmospheric air to enter the chamber1 and as the pressure of the atmospheric air inthe body of the trumpetand the pressure in chamber 1 approach equalization, although fullequalization is probably never attained or even approximately attained,the springs which have been stressed beyond the point necessary tosupport' the valve against the differences in pressure in the device,owing to the momentum of the valve, as referred to above, force thevalve forward and onto its seat, following which, in like manner, theatmosphere in the chamber 1 will again become rarefiedl and the valveunseat and then 9 reseat in rapid vibration. As the valve is seating orreseating the conditions in the trumpet are that a column of`atmospheric air is present therein flowing toward and past the valveand that the confining effect of the walls of the restricted portion ofthe trumpet increase or add to the normal inertia of such column of air.As the valve reseats, it appears that there is in the restricted portionof the trumpet some compression of the atlnospheric air therein with theeffect that the sound waves, the initial generation of which arecompleted upon the reseating of the valve, are projected into anatmosphere which is substantially uniform or consistent and at the sametime supply greater than atmospheric pressure which, of course,accelerates the movement of thesound waves through the vibratory inediumconfined in the trumpet. At the moment of initial generation of thesound waves it will thus be observed that there is a complete severanceor cutting off of the vacuum or reduced pres# sure influence from theair under atmospheric pressure,and thatthe `sound waves are generatedand transmitted to the conducting material in a uniform media.

This results in the discharge of sound waves to the atmosphere of truetone and consistency, resulting in the securing of truc tonal effects onthe ear of the auditor and in the maximum intensity or effectivecarrying power of such sound waves.

As the valve 8 moves toward its seat, it positively interrupts all ofthe column of air which .was heretofore flowing past the valve, as theforce which moves the valve is the pressure of the atmospheric air inthe horn when the space in the rear of the valve is partially evacuatedand as .the restricted Walls of the horn confine the air column somewhatadjacent to the valve, that column of atmospheric air regulates orgoverns the celerity with which the valve returns towards its seat.Therefore, itis found that the vibration of the valve being undercontrol or modilied by the column of air in the horn, the period ofvibration of the valve is regulated or modifie'd to substantially theperiod of vibration of the air column in the horn.

The resonator 5 defines a relatively long` and narrow air columnpreferably-having a very slight taper so that the air column will be ofsubstantial length without any considerable increase in the diameter.The resonator will therefore not reflect sound waves back andforth-across the main longitudinal sound Waves inV disturbance of thelatter, and the resultant tone will therefore be clear and mellow.

Tt is to be observed that the sound wave is produced with slightpressure differential. The fluid pressure in the resonator is normallyatmospheric while that in the conduit 16 is normally slightly belowatmospheric, and

therefore the sound generation is effected in aumedium which is justabout natural as distinguished from pressure types of horns having anoperating pressure which is greatly in excess to the atmosphere, theincreased differential inthe pressure type horn effecting a forced orstrained vibration regardless of the air column in the trumpet. Such aforced vibration of the sound generator is .obviously unnatural and istherefore productive of unnatural noises .and sounds which are raucousand unpleasing to the ear.

Tile have found that under the slight differential under which weoperate our horn that 1 the valve orsound generator is given a Wide'amplitude in its movement and this we account for in the followingmanner:

The valve is given a definite body or mass and is given a resilient`mounting the resiliency of whichis adiusted to the air column Vin theresonator. Then upon providing a pressure differential which issuflicient to in1- tially unseat the valve, a vibration of the latter isset up against the inward movement of the air column from the resonatorinto the chamber l and out through the conduit 16. The sound waves inthe air column within the resonator lnove forwardly and producereflected sound waves, resultingin surges or pulsations which aresubstantially in rhythm and synchronism with the vibration of the valve.This results in a regenerative action on the valve 8 so as to increaseits amplitude over and above that Vinitially imparted to it by thepressure differential alone.

It is believed that this regenerative effect will be more clearlyunderstood by referring to Figs. 4 and 5 which depict our theory of thissound regeneration. In these figures the resonator 5 is diagrammaticallyillustrated along with the sound generator or valve 8. Assuming that thevalve has been withdrawn from its seat by the initial pressuredifferential and the air column in the resonator is moving inwardly pastthe valve, with the latter starting tpward its seat as indicated by thearrow in Fig. 5, there will be a slight rarefaction at the inner end ofthe resonator. But as the valve mass moves quickly to its seat againstthe inward movement of the air column 1t will tend to slightly compressthe air at the seat, so that when the latter is fully seated there is apressure built up in the inner end of the resonator acting increasinglygreater upon the valve to unseat the same. The trumpet of the resonatorhavin@ a length substantially equal to one half of the length of thesound wave, there will be a crest or condensation at the inner end ofthe air column as the valve seats with-a rarefaction or valley at theouter end of the resonator, and as the crest moves outwardly to theouter end of the air column there will be a rarefaction at the inner endand that these pulsations will surge and reflect back and forth withinthe resonator substantially in synchronism with the movement of thevalve. rTherefore after the valve has seated and built up a pressure atthe inner end of the air column the reflected sound wave or surge movinginwardly strikes against the valve substantially at the moment the valveis ready again to leave its seat so that the inwardly moving surge givesto the valve an added impetus.

This occurs for each movement of the valve and builds up a greateramplitude of movement so that as the valve unseats in a larger volume ofatmosphere, increasing the inward movement of the air column and havinga faster moving column of air to seat against as the valve returns toits seat. Thus the valve action isbuilt up in a regenerative manner tosuch an extent that in tests made it has been found that the movingvalve body will rebound against the spring support 17, an extent ofmovement which is not attained in the absence of the resonator. Tnaddition to this regenerative movement in the valve there is also aregenerative production of sound whereby the volume of thesound waves isincreased to carry long distances, the sound waves being produced underthe natural period of vibration of the valve, in the presence of a smallpressure differential.

As an example of this tuned frequency or relationship between the soundgenerator and the resonator, we provide a resonator having anapproximate length of 191/4 with an inside diameter at its smaller endof approximately 1/8 flaring to a diameter at its larger it will draw @lmovement in the trumpet and end, Where it merges into the bell,ofapproximately 11/4; The valve seat has' anv inner diameter of f on whichseats the valve disc having a diameter of 2 The valve disc 5; and itsbody or mass has a Weight of 6% grams and is suspended from four cornerposts, diagonally spaced apart 2%, by four coiled springs normally about5%, in length in addition to their attaching terminals or loops. Thenormal outsideidiameter of the spring coil is and When the springs arestretched from their posts 13 to suspend the valve, as shown in thedrawings, there is an approximate pull of three pounds and three 15ounces.

rlhe pressure or spring support 17 engages the springs adjacent theirintermediate portions and is adjusted to give the proper resiliency inthe mounting of the valve by turn- 20 ,ing the screw 18 inwardly.

The foregoing dimensions, Weights and other factors are given inapproximate figures for producing a tuned valve vibration in synchronismwith the air column in the re-` effsonator Whereb the surges or ulses inthe mit t;

air column produce a regenerative action not only on the valve butA alsoonthe sound Waves.

ylhe sound generator per se constitutes the subject-matter of ourco-pending application 3@ filed @ctober 3, 1930,1inder Serial No.486,228,

tige present application being a division thereo What is claimed is:

1.' An audible signal for automotive vei5`hicles comprising acone-shaped horn opening through a valve seat, a valve suspended at theapex of said horn to vibrate on the seat, said horn 'being of size andshape to utilize the surge of an air column to effect a 40 ltuned,timed, synchronous mouvement of the valve in the direction of thesurging air, and `means for starting and aiding the surging of the airby moving the said valve by atmospheric pressure When the said valve isplaced `in communication with the intake manifold of an internalcombustion engine.

2. In a fluid operated sound producing device, tlie combination of aresiliently mounted valve suitably loaded so as to have a natural 5'0'movement of a fairly definite periodicity,

with a trumpet of suitable length and proportion so that the naturalperiodicity of the sound Wave in its air column will correspondsubstantially with that of the valve or valve assembly, said trumpetbeing tapered and @0 by have a regenerative effect upon the valvethereby to increase the amplitude of its movement, in order that thisincreased .amplitude ivill in turn cause a further regenerative in-`crease in the intensity of the sound vvave tnereby produce a furtherincrease in the volume of the sound emitted from the trumpet.

3. A method of producing a signal note or I tone consisting in providinga resonator having a definite air column confined at one end by acylindrical body and opening therefrom through an annular valve seat,resiliently supporting a sound generating valveof a definite inertia onthe seat, adjusting the tension of the spring support whereby the rateof vibration of the valve to and from the seat Will be in synchronismwith the reflected pulsations in the air column to increase theamplitude of the valve and produce a regenerative action, and thenproviding a pressure diiferential on opposite sides of the valve tovibrate the latter.

il. ln a fluid operated sound producing device for motor vehicles, thecombination of a resiliently supported valve suitably loaded or of asuitable mass so as to have a movement of a substantially definiteperiodicity, With a trumpet of suitable length and proportion so thatthe natural periodicity of the sound Waves in its air column willcorrespond substantiaily with that of the valve, said trumpet beingarranged with its smaller end in communication with said valve.

5. ln a Huid operated sound producing device for motor vehicles, thecombination of a resiliently mounted valve of a mass to have a fairlydefinite periodicity to its natural movement, with a tapered trumpet .ofa length and proportion that the natural periodicity of the sound Wavesin its air column-Will correspond substantially with that of the valve,said trumpet being arranged Withl its smaller end in communication withsaid valve through a cooperating valve seat.

6. The method of manufacturing tuned signalling horns, consisting inconnecting a resonator, Which has a definite air column opening at itssmaller end througha valve seat, to a valve of a definite body inertiaand Which is resiliently supporte-d for vibratory movement to and fromsaid seat for interrupting the movement of the air column in theresonator; establishing an air flovv from the resonator through thevalve seat to move the valve avvay from its seat in a man-ner to set itin sound generating vibration, and the-n varying the resiliency in thesupport of the valve to synchronize the vibration of the lattei' Withthe pulses in the air column of the resonator for the regeneration ofsound Waves.

t". t method of producing sound of predetermined characteristicsconsisting in induc ing a column of atmospheric air ,to move through acolumn confining device, and in periodically and forcibly interruptingand n releasing said movement in timed frequency `commensurate with thevibratory period of said column so confined.

Eil .ln a sound producing device, means for til) titi

releasably confining a sound Wave transmitting and character changingmedium of a 1 predetermined period of vibration, a restricted passageportion in said device, a valve 5 adapted to seat on and close therestricted portion of said device, means for causing said' medium tomove into the device and past said valve, said valve being adapted andarranged to periodically close said valve against the flow of saidmedium to interrupt and stop the passage of said medium at a frequency Acommensurate with the vibratory period of said medium, whereby saidmedium is rendered fully vibrant.

w 9. A horn comprising a support having a passage therethrough and anannular seat about the passage at one sideof the support, l vibratoryvalve means resiliently yieldable to and from said seatand operable witha predetermined rate of vibrationfor the production of sound, aresonator defining an air column acting to reinforce the `sound wavestherein, said resonator opening at one endl to the atmosphere and havingits opposite end communicatingly connected to the passage of the supportat the side thereof opposite from the seat, and means for creating aflow of Huid from the resonator through the passage and past the valvemeans.

10. A horn comprising a resonator con'- fininga definite air column, acasing having a chamber into which one'end of the resonator opens, anannular seat Within the chams ber through which communication is hadwith the resonator, avalving member coacting with the seat to interruptintermittently the movement of the air Acolumn from the-resonator intothe chamber through the seat, anda resilient support for the valvingmember 40 adjusted to return the llatter to its seat in rhythm withI thesound Wave surges in the air column of the resonator to create a`regenerative action on the valving member for enhancing its movement. Y

11. An audible signal comprising a trumpet confining an air column atsubstantially atmospheric pressure and having a definite naturalperiodicity for sound waves, said trumpet iared and opened to theatmosphere at one end and opening at its opposite end through l'a seat,and a member vibratory on the seat inthe presence of such atmosphericpressure at a frequency of vibration in synchronism with the naturalperiodicity of the sound Waves in the air-column whereby thesynchronized air impulses in the airl column will impinge upon 'the'vibratory member in a regenerative capacity to increase the amplitude ofmovement of said vibratory member in the presence of such atmosphericpressure, and means for setting said member in vibration.

' HENRY HUEBER. w ERWIN C. HORTON.

